我正在尝试获取相机预览并在 onPreviewFrame() 中更改它并将其显示给用户。我已经实现了所需的功能，但问题在于相机预览的大小。它总是占用屏幕的较小部分，我想将其设为全屏，即想要拍摄应填充设备整个屏幕的相机预览。我有阅读并尝试了网上可用的任何解决方案，但它们都不适用于我的情况。这是 Surface View 类：
public class MySurfaceView extends SurfaceView implements Callback, Camera.PreviewCallback, android.view.SurfaceHolder.Callback {
private static final String TAG = "MySurfaceView";
private int width;
private int height;
public SurfaceHolder mHolder;
private Camera mCamera;
private int[] rgbints;
private int mMultiplyColor;
public MySurfaceView(Context context, AttributeSet attrs , Camera camera ,
int width , int height)
{
super(context, attrs);
mCamera = camera;
this.width = width;
this.height = height;
mHolder = getHolder();
mHolder.addCallback(this);
mMultiplyColor = getResources().getColor(R.color.honeydew);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
{
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
synchronized (this) {
this.setWillNotDraw(false); // This allows us to make our own draw calls to this canvas
rgbints = new int[width * height];
// try { mCamera.setPreviewDisplay(holder); } catch (IOException e)
// { Log.e("Camera", "mCamera.setPreviewDisplay(holder);"); }
mCamera.startPreview();
mCamera.setPreviewCallback(this);
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
synchronized (this) {
try
{
CameraActivity cameraActivity = new CameraActivity();
cameraActivity.releaseCamera();
cameraActivity = null;
} catch (Exception e) {
Log.e("Camera", e.getMessage());
}
}
}
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
Canvas canvas = null;
if (mHolder == null)
{
return;
}
try {
synchronized (mHolder)
{
canvas = mHolder.lockCanvas(null);
int canvasWidth = canvas.getWidth();
int canvasHeight = canvas.getHeight();
decodeYUV(rgbints, data, width, height);
// draw the decoded image, centered on canvas
canvas.drawBitmap(rgbints, 0, width, canvasWidth-((width+canvasWidth)>>1), canvasHeight-((height+canvasHeight)>>1), width, height, false, null);
// use some color filter
canvas.drawColor(mMultiplyColor, Mode.MULTIPLY);
}
} catch (Exception e){
e.printStackTrace();
} finally {
// do this in a finally so that if an exception is thrown
// during the above, we don't leave the Surface in an
// inconsistent state
if (canvas != null)
{
mHolder.unlockCanvasAndPost(canvas);
canvas = null;
}
}
}
public void decodeYUV(int[] out, byte[] fg, int width, int height) throws NullPointerException, IllegalArgumentException {
int sz = width * height;
if (out == null)
throw new NullPointerException("buffer out is null");
if (out.length < sz)
throw new IllegalArgumentException("buffer out size " + out.length + " < minimum " + sz);
if (fg == null)
throw new NullPointerException("buffer 'fg' is null");
if (fg.length < sz)
throw new IllegalArgumentException("buffer fg size " + fg.length + " < minimum " + sz * 3 / 2);
int i, j;
int Y, Cr = 0, Cb = 0;
for (j = 0; j < height; j++) {
int pixPtr = j * width;
final int jDiv2 = j >> 1;
for (i = 0; i < width; i++) {
Y = fg[pixPtr];
if (Y < 0)
Y += 255;
if ((i & 0x1) != 1) {
final int cOff = sz + jDiv2 * width + (i >> 1) * 2;
Cb = fg[cOff];
if (Cb < 0)
Cb += 127;
else
Cb -= 128;
Cr = fg[cOff + 1];
if (Cr < 0)
Cr += 127;
else
Cr -= 128;
}
int R = Y + Cr + (Cr >> 2) + (Cr >> 3) + (Cr >> 5);
if (R < 0)
R = 0;
else if (R > 255)
R = 255;
int G = Y - (Cb >> 2) + (Cb >> 4) + (Cb >> 5) - (Cr >> 1) + (Cr >> 3) + (Cr >> 4) + (Cr >> 5);
if (G < 0)
G = 0;
else if (G > 255)
G = 255;
int B = Y + Cb + (Cb >> 1) + (Cb >> 2) + (Cb >> 6);
if (B < 0)
B = 0;
else if (B > 255)
B = 255;
out[pixPtr++] = 0xff000000 + (B << 16) + (G << 8) + R;
}
}
}
public void showSupportedCameraFormats(Parameters p) {
List<Integer> supportedPictureFormats = p.getSupportedPreviewFormats();
Log.d(TAG, "preview format:" + cameraFormatIntToString(p.getPreviewFormat()));
for (Integer x : supportedPictureFormats) {
Log.d(TAG, "suppoterd format: " + cameraFormatIntToString(x.intValue()));
}
}
@SuppressWarnings("deprecation")
private String cameraFormatIntToString(int format) {
switch (format) {
case PixelFormat.JPEG:
return "JPEG";
case PixelFormat.YCbCr_420_SP:
return "NV21";
case PixelFormat.YCbCr_422_I:
return "YUY2";
case PixelFormat.YCbCr_422_SP:
return "NV16";
case PixelFormat.RGB_565:
return "RGB_565";
default:
return "Unknown:" + format;
}
}
}
这是调用者类：
public class CameraActivity extends Activity {
private Camera mCamera;
private MySurfaceView surfaceView;
private RelativeLayout relativeLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
releaseCamera();
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
releaseCamera();
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
mCamera = Camera.open();
Camera.Parameters p = mCamera.getParameters();
Size size = p.getPreviewSize();
int width = size.width;
int height = size.height;
p.setPreviewFormat(ImageFormat.JPEG);
mCamera.setParameters(p);
surfaceView = new MySurfaceView(this, null , mCamera ,width , height);
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
surfaceView.setLayoutParams(layoutParams);
relativeLayout = (RelativeLayout)findViewById(R.id.relativeLayout);
relativeLayout.addView(surfaceView);
surfaceView.showSupportedCameraFormats(p);
}
public void releaseCamera()
{
if (mCamera != null)
{
mCamera.stopPreview();
mCamera.setPreviewCallback(null);
surfaceView.getHolder().removeCallback(surfaceView);
mCamera.release(); // release the camera for other applications
mCamera = null;
surfaceView.mHolder.removeCallback(surfaceView);
surfaceView.mHolder = null;
surfaceView = null;
relativeLayout.removeAllViews();
relativeLayout.removeAllViewsInLayout();
relativeLayout = null;
}
}
}
请帮助我。提前致谢。
编辑：
Xml 是：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:id="@+id/relativeLayout"
android:layout_height="match_parent" >
</RelativeLayout>
relativelayout 倾向于采用 Linearlayout 并在其中放入framelayout：
<FrameLayout
android:id="@+id/preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1" >
</FrameLayout>
然后在其中设置camerapreview：
surfaceView = new MySurfaceView(this, null , mCamera ,width , height);
((FrameLayout) findViewById(R.id.preview)).addView(surfaceView);
相机预览.java
class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private static final String TAG = "Preview";
SurfaceHolder mHolder;
public Camera camera;
CameraPreview(Context context) {
super(context);
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where
// to draw.
if(camera == null){
camera = Camera.open();
camera.setDisplayOrientation(90);
try {
camera.setPreviewDisplay(holder);
camera.setPreviewCallback(new PreviewCallback() {
public void onPreviewFrame(byte[] data, Camera arg1) {
CameraPreview.this.invalidate();
}
});
} catch (IOException e) {
camera.release();
camera = null;
}
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
// Because the CameraDevice object is not a shared resource, it's very
// important to release it when the activity is paused.
if(camera!=null){
camera.stopPreview();
camera.setPreviewCallback(null);
camera.release();
camera = null;
}
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// Now that the size is known, set up the camera parameters and begin
// the preview.
Camera.Parameters parameters = camera.getParameters();
// parameters.setPreviewSize(w, h);
camera.setParameters(parameters);
camera.startPreview();
}
@Override
public void draw(Canvas canvas) {
super.draw(canvas);
Paint p= new Paint(Color.RED);
Log.d(TAG,"draw");
canvas.drawText("PREVIEW", canvas.getWidth()/2, canvas.getHeight()/2, p );
}
public void releaseCameraAndPreview() {
if (camera != null) {
camera.release();
camera = null;
}
}
}
就我而言，我通过将这一行
android:hardwareAccelerated="true"captureActivityAndroidManifest.xml这是我在
activity_capture.xml<androidx.camera.view.PreviewView
android:id="@+id/preview"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
这是
CaptureActivityAndroidManifest.xml<activity
android:name=".view.CaptureActivity"
android:exported="false"
android:hardwareAccelerated="true" />